The present invention relates to novel olefin polymerization catalysts, transition metal compounds and processes for olefin polymerization using the olefin polymerization catalysts.
The present invention also relates to xcex1-olefin/conjugated diene copolymers which have narrow molecular weight distribution and are favorably used as rubbers.
As olefin polymerization catalysts, xe2x80x9cKaminsky catalystsxe2x80x9d are well known. The Kaminsky catalysts have extremely high polymerization activities, and by the use of them, polymers of narrow molecular weight distribution can be obtained. Transition metal compounds which are known as those employable for the Kaminsky catalysts are, for example, bis(cyclopentadienyl)zirconium dichloride (see: Japanese Patent Laid-Open Publication No. 19309/1083) and ethylenebis(4,5,6,7-tetrahydroindenyl)zirconium dichloride (see: Japanese Patent Laid-Open Publication No. 130314/1086). It is also known that the olefin polymerization activities or the properties of the resulting polyolefins greatly vary when different transition metal compounds are used in the polymerization. Further, transition metal compounds having a ligand of diimine structure have been recently proposed as novel olefin polymerization catalysts (see: International Patent Publication No. 9623010).
By the way, polyolefins generally have excellent mechanical properties, and therefore they are used in many fields such as fields of various molded products. However, with variation of requirements for the polyolefins, polyolefins of various properties have been desired in recent years. Moreover, increase of productivity has been also desired.
Under such circumstances as mentioned above, there has been desired development of olefin polymerization catalysts having excellent olefin polymerization activities and capable of producing polyolefins of excellent properties.
It is well known that copolymerization of several kinds of xcex1-olefins and non-conjugated dienes proceeds when Ziegler-Natta polymerization catalysts are used. Since the copolymers thus obtained are useful as rubbers, copolymers of various types have been produced. However, the non-conjugated dienes used in the copolymerization are generally expensive and have low reactivity. Therefore, diene components which are inexpensive and have high reactivity are desired.
Examples of such diene components include conjugated dienes such as 1,3-butadiene and isoprene. Though these conjugated dienes are more inexpensive and have higher reactivity as compared with the conventional non-conjugated dienes, they have problem such that the activities are markedly lowered or only ununiform copolymers of wide composition distribution or wide molecular weight distribution are obtained if the copolymerization is conducted by the use of the conventional Ziegler-Natta polymerization catalysts. In case of a Ziegler-Natta catalyst system using a vanadium compound, the polymerization activities are extremely low, though relatively uniform copolymers are obtainable. In the circumstances, copolymerization of ethylene and butadiene using metallocene catalysts which have been studied extensively and thus known to exhibit high polymerization activities has been investigated (National Publication of International Patent No. 501633/1989).
In the above case, however, it has been reported that from the diene unit and ethylene incorporated into the polymer form together cyclopentane skeleton in the polymer chain, and that the proportion of the cyclopentane skeleton becomes not less than 50% of all the diene units. The conversion of double bonds of the diene unit into the cyclopentane skeleton is very disadvantageous in the procedure of xe2x80x9cvulcanizationxe2x80x9d required to use the copolymers as rubbers. Further, the cyclopentane skeleton is an unfavorable skeleton because it functions to increase glass transition temperature of the copolymers and is detrimental to the low-temperature properties of the rubbers.
Under these circumstances, as mentioned above, there has been eagerly desired development of copolymers of xcex1-olefins and conjugated dienes, which have narrow molecular weight distribution and uniform composition and contain almost no cyclopentane skeleton in their polymer chains.
It is an object of the present invention to provide an olefin polymerization catalyst having excellent olefin polymerization activities.
It is another object of the invention to provide a novel transition metal compound useful for such catalyst.
It is a further object of the invention to provide a process for olefin polymerization using the catalyst.
It is a still further object of the invention to provide an xcex1-olefin/conjugated diene copolymer having a narrow molecular weight distribution and containing almost no cyclopentane skeleton in its polymer chain.
The first olefin polymerization catalyst according to the present invention comprises:
(A) a transition metal compound represented by the following formula (I), and
(B) at least one compound selected from:
(B-1) an organometallic compound,
(B-2) an organoaluminum oxy-compound, and
(B-3) a compound which reacts with the transition metal compound (A) to form an ion pair: 
wherein M is a transition metal atom of Group 3 to Group 11 of the periodic table,
m is an integer of 1 to 6,
R1 to R6 may be the same or different, and are each a hydrogen atom, a halogen atom, a hydrocarbon group, a heterocyclic compound residue, an oxygen-containing group, a nitrogen-containing group, a boron-containing group, a sulfur-containing group, a phosphorus-containing group, a silicon-containing group, a germanium-containing group or a tin-containing group, and two or more of them may be bonded to each other to form a ring,
when m is 2 or greater, two of the groups R1 to R6 may be bonded to each other, with the proviso that the groups R1 are not bonded to each other,
n is a number satisfying a valence of M, and
X is a hydrogen atom, a halogen atom, a hydrocarbon group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a boron-containing group, an aluminum-containing group, a phosphorus-containing group, a halogen-containing group, a heterocyclic compound residue, a silicon-containing group, a germanium-containing group or a tin-containing group, and when n is 2 or greater, plural groups X may be the same or different and may be bonded to each other to form a ring.
In the present invention, R6 in the formula (I) is preferably a halogen atom, a hydrocarbon group, a heterocyclic compound residue, an oxygen-containing group, a nitrogen-containing group, a boron-containing group, a sulfur-containing group, a phosphorus-containing group, a silicon-containing group, a germanium-containing group or a tin-containing group.
In the present invention, the transition metal compound represented by the formula (I) is preferably a transition metal compound represented by the following formula (I-a): 
wherein M is a transition metal atom of Group 3 to Group 11 of the periodic table,
m is an integer of 1 to 3,
R1 to R6 may be the same or different, and are each a hydrogen atom, a halogen atom, a hydrocarbon group, a heterocyclic compound residue, a hydrocarbon-substituted silyl group, a hydrocarbon-substituted siloxy group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an acyl group, an ester group, a thioester group, an amido group, an imido group, an amino group, an imino group, a sulfonester group, a sulfonamido group, a cyano group, a nitro group, a carboxyl group, a sulfo group, a mercapto group or a hydroxyl group, and two or more of them may be bonded to each other to form a ring,
when m is 2 or greater, two of the groups R1 to R6 may be bonded to each other, with the proviso that the groups R1 are not bonded to each other,
n is a number satisfying a valence of M, and
X is a hydrogen atom, a halogen atom, a hydrocarbon group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a boron-containing group, an aluminum-containing group, a phosphorus-containing group, a halogen-containing group, a heterocyclic compound residue, a silicon-containing group, a germanium-containing group or a tin-containing group, and when n is 2 or greater, plural groups X may be the same or different and may be bonded to each other to form a ring.
In the above formula (I-a), R6 is preferably a halogen atom, a hydrocarbon group, a heterocyclic compound residue, a hydrocarbon-substituted silyl group, a hydrocarbon-substituted siloxy group, an alkoxy group, an alkylthio group, an aryloxy group, a arylthio group, an acyl group, an ester group, a thioester group, an amido group, an imido group, an amino group, an imino group, a sulfonester group, a sulfonamido group, a cyano group, a nitro group, a carboxyl group, a sulfo group, a mercapto group or a hydroxyl group.
Further, the transition metal compound represented by the formula (I) is preferably a transition metal compound represented by the following formula (I-a-1): 
wherein M is a transition metal atom of Group 3 to Group 11 of the periodic table,
m is an integer of 1 to 3,
R1 to R6 may be the same or different, and are each a hydrogen atom, a halogen atom, a hydrocarbon group, a heterocyclic compound residue, a hydrocarbon-substituted silyl group, a hydrocarbon-substituted siloxy group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an acyl group, an ester group, a thioester group, an amido group, an imido group, an amino group, an imino group, a sulfonester group, a sulfonamido group, a cyano group, a nitro group or a hydroxyl group, and two or more of them may be bonded to each other to form a ring,
when m is 2 or greater, two of the groups R1 to R6 may be bonded to each other, with the proviso that the groups R1 are not bonded to each other,
n is a member satisfying a valence of M, and
X is a hydrogen atom, a halogen atom, a hydrocarbon group of 1 to 20 carbon atoms, a halogenated hydrocarbon group of 1 to 20 carbon atoms, an oxygen-containing group, a sulfur-containing group or a silicon-containing group, and when n is 2 or greater, plural groups X may be the same or different and may be bonded to each other to form a ring.
In the formula (I-a-1), R6 is preferably a halogen atom, a hydrocarbon group, a heterocyclic compound residue, a hydrocarbon-substituted silyl group, a hydrocarbon-substituted siloxy group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an acyl group, an ester group, a thioester group, an amido group, an imido group, an amino group, an imino group, a sulfonester group, a sulfonamido group, a cyano group, a nitro group or a hydroxyl group.
In the present invention, further, the transition metal compound represented by the formula (I) is preferably a transition metal compound represented by the following formula (I-b): 
wherein M is a transition metal atom of Group 3 to Group 11 of the periodic table,
m is an integer of 1 to 6,
R1 to R6 may be the same or different, and are each a hydrogen atom, a halogen atom, a hydrocarbon group, a hydrocarbon-substituted silyl group, an alkoxy group, an aryloxy group, an ester group, an amido group, an amino group, a sulfonamido group, a cyano group or a nitro group, and two or more of them may be bonded to each other to form a ring, and
when m is 2 or greater, two of the groups R1 to R6 may be bonded to each other, with the proviso that the groups R1 are not bonded to each other.
In the formula (I-b), R6 is preferably a halogen atom, a hydrocarbon group, a hydrocarbon-substituted silyl group, an alkoxy group, an aryloxy group, an ester group, an amido group, an amino group, a sulfonamido group, a cyano group or a nitro group.
It is preferred that M in the transition metal compound (A) is at least one transition metal atom selected from Groups 3 to 5 and Group 9 of the periodic table.
The first olefin polymerization catalyst according to the invention may further comprise a carrier (C), in addition to the transition metal compound (A) and at least one compound (B) selected from the organometallic compound (B-1), the organoaluminum oxy-compound (B-2) and the compound (B-3) which reacts with the transition metal compound (A) to form an ion pair.
The first process for olefin polymerization according to the present invention comprises polymerizing or copolymerizing an olefin in the presence of the above-mentioned olefin polymerization catalyst.
The second olefin polymerization catalyst according to the present invention comprises:
(Axe2x80x2) a transition metal compound represented by the following formula (II), and
(B) at least one compound selected from:
(B-1) an organometallic compound,
(B-2) an organoaluminum oxy-compound, and
(B-3) a compound which reacts with the transition metal compound (Axe2x80x2) to form an ion pair. 
wherein M is a transition metal atom of Group 3 to Group 11 of the periodic table,
R1 to R10 may be the same or different, and are each a hydrogen atom, a halogen atom, a hydrocarbon group, a heterocyclic compound residue, an oxygen-containing group, a nitrogen-containing group, a boron-containing group, a sulfur-containing group, a phosphorus-containing group, a silicon-containing group, a germanium-containing group or a tin-containing group, and two or more of them may be bonded to each other to form a ring,
n is a number satisfying a valence of M,
X is a hydrogen atom, a halogen atom, a hydrocarbon group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a boron-containing group, an aluminum-containing group, a phosphorus-containing group, a halogen-containing group, a heterocyclic compound residue, a silicon-containing group, a germanium-containing group or a tin-containing group, and when n is 2 or greater, plural groups X may be the same or different and may be bonded to each other to form a ring, and
Y is a divalent bonding group containing at least one element selected from the group consisting of oxygen, sulfur, carbon, nitrogen, phosphorus, silicon, selenium, tin and boron, and when it is a hydrocarbon group, the hydrocarbon group has 3 or more carbon atoms.
In the above formula (II), at least one of R6 and R10 is preferably a halogen atom, a hydrocarbon group, a heterocyclic compound residue, an oxygen-containing group, a nitrogen-containing group, a boron-containing group, a sulfur-containing group, a phosphorus-containing group, a silicon-containing group, a germanium-containing group or a tin-containing group.
The transition metal compound represented by the formula (II) is preferably a transition metal compound represented by the following formula (II-a). 
wherein M is a transition metal atom of Group 3 to Group 11 of the periodic table,
R1 to R10 may be the same or different, they are each a hydrogen atom, a halogen atom, a hydrocarbon group, a hydrocarbon-substituted silyl group, an alkoxy group, an aryloxy group, an ester group, an amido group, an amino group, a sulfonamido group, a cyano group or a nitro group, and two or more of them may be bonded to each ocher to form a ring,
n is a number satisfying a valence of M,
X is a hydrogen atom, a halogen atom, a hydrocarbon group of 1 to 20 carbon atoms, a halogenated hydrocarbon group of 1 to 20 carbon atoms, an oxygen-containing group, a sulfur-containing group or a silicon-containing group, and when n is 2 or greater, plural groups X may be the same or different and may be bonded to each other to form a ring, and
Y is a divalent bonding group containing at least one element selected from the group consisting of oxygen, sulfur, carbon, nitrogen, phosphorus, silicon, selenium, tin and boron, and when it is a hydrocarbon group, the hydrocarbon group has 3 or more carbon atoms.
In the above formula (II-a), at least one of R6 and R10 is preferably a halogen atom, a hydrocarbon group, a hydrocarbon-substituted silyl group, an alkoxy group, an aryloxy group, an ester group, an amido group, an amino group, a sulfonamido group, a cyano group or a nitro group.
It is preferred that M in the transition metal compound (Axe2x80x2) is at least one transition metal atom from Groups 4 and 5 of the periodic table.
The second olefin polymerization catalyst according to the invention may further comprise a carrier (C), in addition to the transition metal compound (Axe2x80x2) and at least one compound (B) selected from the organometallic compound (B-1), the organoaluminum oxy-compound (B-2) and the compound (B-3) which reacts with the transition metal compound (Axe2x80x2) to form an ion pair.
The second process for olefin polymerization comprises polymerizing or copolymerizing an olefin in the presence of the above-mentioned olefin polymerization catalyst.
The novel transition metal compound according to the present invention is represented by the following formula (III): 
wherein M is a transition metal atom of Group 4 or Group 5 of the periodic table,
m is an integer of 1 to 3,
R1 is a hydrocarbon group, a hydrocarbon-substituted silyl group, a hydrocarbon-substituted siloxy group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an ester group, a thioester group, a sulfonester group or a hydroxyl group,
R2 to R5 may be the same or different, and are each a hydrogen atom, a halogen atom, a hydrocarbon group, a heterocyclic compound residue, a hydrocarbon-substituted silyl group, a hydrocarbon-substituted siloxy group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an ester group, a thioester group, an amido group, an imido group, an amino group, an imino group, a sulfonester group, a sulfonamido group, a cyano group, a nitro group, a carboxyl group, a sulfo group, a mercapto group or a hydroxyl group,
R6 is a halogen atom, a hydrocarbon group, a hydrocarbon-substituted silyl group, a hydrocarbon-substituted siloxy group, an alkoxy group, an alkylthio group, an aryloxy group, an arylthio group, an ester group, a thioester group, an amido group, an imido group, an imino group, a sulfonester group, a sulfonamido group or a cyano group,
two or more of R1 to R6 may be bonded to each other to form a ring,
when m is 2 or greater, two of the groups R1 to R6 may be bonded to each other, with the proviso that the groups R1 are not bonded to each other,
n is a number satisfying a valence of M, and
X is a halogen atom, a hydrocarbon group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a boron-containing group, an aluminum-containing group, a phosphorus-containing group, a halogen-containing group, a heterocyclic compound residue, a silicon-containing group, a germanium-containing group or a tin-containing group, and when n is 2 or greater, plural groups X may be the same or different and may be bonded to each other to form a ring.
The above-mentioned transition metal compound is preferably a compound represented by the following formula (III-a): 
wherein M is a transition metal atom of Group 4 or Group 5 of the periodic table,
m is an integer of 1 to 3,
R1 to R5 may be the same or different, and are each a hydrocarbon group, an alkoxy group or a hydrocarbon-substituted silyl group,
R6 is a halogen atom, a hydrocarbon group, a hydrocarbon-substituted silyl group, an alkoxy group, a alkylthio group or a cyano group,
two or more of R1 to R6 may be bonded to each other to form a ring,
when m is 2 or greater, two groups of the groups R1 to R6 may be bonded to each other, with the proviso that the groups R1 are not bonded to each other,
n is a number satisfying a valence of M, and
X is a halogen atom, a hydrocarbon group, an oxygen-containing group, a sulfur-containing group, a nitrogen-containing group, a halogen-containing group or a silicon-containing group, and when n is 2 or greater, plural groups X may be the same or different and may be bonded to each other to form a ring.
In the formula (III-a), m is preferably 2.
The third olefin polymerization catalyst according to the present invention comprises:
(Axe2x80x3) a novel transition metal compound as described above, and
(B) at least one compound selected from:
(B-1) an organometallic compound,
(B-2) an organoaluminum oxy-compound, and
(B-3) a compound which reacts with the transition metal compound (A) to form an ion pair.
The third olefin polymerization catalyst according to the present invention may further comprise a carrier (C) in addition to the transition metal compound (Axe2x80x3) and at least one compound (B) selected from the organometallic compound (B-1), the organoaluminum oxy-compound (B-2) and the compound (B-3) which reacts with the transition metal compound (Axe2x80x3) to form an ion pair.
The third process for olefin polymerization comprises polymerizing or copolymerizing an olefin in the presence of the above-mentioned olefin polymerization catalyst.
The xcex1-olefin/conjugated diene copolymer according to the present invention is an xcex1-olefin/conjugated diene copolymer having a molecular weight distribution (Mw/Mn) of not more than 3.5, a content of constituent units derived from an xcex1-olefin in the range of 1 to 99.9% by mol and a content of constituent units derived from a conjugated diene in the range of 99 to 0.1% by mol, in which the polymer chain contains 1,2-cyclopentane skeleton derived from the conjugated diene in an amount of not more than 1% by mol, and preferably the polymer chain does not substantially contain the 1,2-cyclopentane skeleton.
In the xcex1-olefin/conjugated diene copolymer according to the invention, it is preferred that the content of the constituent units derived from the xcex1-olefin is in the range of 50 to 99.9% by mol and the content of the constituent units derived from the conjugated diene is in the range of 50 to 0.1% by mol.
In the xcex1-olefin/conjugated diene copolymer according to the invention, it is preferred that the xcex1-olefin is ethylene and/or propylene and the conjugated diene is butadiene and/or isoprene.